Question

State the differences between charging by contact and charging by induction.

Answer 1

Charging by conduction - useful for charging metals and other conductors. If a charged object touches a conductor, some charge will be transferred between the object and the conductor, charging the conductor with the same sign as the charge on the object. 

Charging by induction - also useful for charging metals and other conductors. Again, a charged object is used, but this time it is only brought close to the conductor, and does not touch it. If the conductor is connected to ground (ground is basically anything neutral that can give up electrons to, or take electrons from, an object), electrons will either flow on to it or away from it. When the ground connection is removed , the conductor will have a charge opposite in sign to that of the charged object.

Answer 2

Charging by contact: When an object is charged +ve or -ve by physically being in contact with each other.ex in electroscope

Charging by induction: When an object is charged +ve or -ve without being physically contact with each other.